Geothermal Exploration of the Suio Area, Central Italy.

The Suio area is part of the peri-Tyrrhenian sector of central Italy, a thermally anomalous area where CO2-pressurized hydrothermal reservoirs develop in a complex geodynamic setting. Thermalism is commonly attributed to the post-orogenic magmatic activity, which occurred from Pliocene to Quaternary in response to an extensional regime. The Suio area shows thermo-mineral springs located in a boundary zone between the NW side of the Roccamonfina Volcanic Complex (RVC) and the Aurunci carbonatic range. The chemical composition of these springs reflects the unique lithology of the aquifer where they are flowing. The relationship between volcanic and carbonate complexes suggests that mineralization is strongly enhanced by acid gas emissions (CO2, H2S) and high temperatures. As a final product, the intense water–rock interaction brings highly mineralized waters that could be divided in two sub-groups according to the amount of solubilized CaCO3 or to the degree of interaction with carbonatic rocks. All Suio thermal waters have a very similar Mg/(Na+K) and Na/K ratio (0.65 and 3, respectively) confirming their circulation into the carbonatic complex, with an enrichment of fluids deriving from RVC. Common geothermometers used in order to evaluate the reservoir equilibrium temperature indicate values ranging from 125° to 150°C. The present acquired data suggest that the area could be a suitable location for direct applications of the geothermal resource. Starting from the hydro-geologic model, the authors are performing numerical simulations, verifying the conceptual-model and comparing simulated results with recollected data.